汇编程序45：检测点13.2 (loop指令的中断例程)

 安装程序：
 assume cs:code
 //loop指令的替代实现
 code segment
     start:
           mov ax,cs
           mov ds,ax
           mov si,offset sub1
           mov ax,0020h
           mov es,ax
           mov di,
           mov bx,offset sub2 - offset sub1
           cld
           rep movsb
           mov ax,
           mov es,ax
           mov word ptr es:[7ch*],200h
           mov word ptr es:[7ch*+],
           mov ax,4c00h
           int 21h
      sub1:
           push bp
           mov bp,sp
           dec cx
           jcxz s0
           add [bp+],bx
        s0:
           pop bp
           iret
      sub2:
           nop
 code ends

 end start

 测试程序：
 assume cs:code
 //将80个!显示在屏幕上
 code segment
     start:
           mov ax,0b800h
           mov es,ax
           mov di,*
           mov bx,offset s - offset se
           mov cx,
         s:
           mov byte ptr es:[di],'!'
           add di,
           int 7ch //安装程序,实现loop s功能
        se:
           mov ax,4c00h
           int 21h
 code ends

 end start